Year 2000 Issue

[maay100@bgumail.bgu.ac.il (Quastel)]

Dear Otto,                                              June 13, 1997

        If we assume from your note that the day is slowing up by 0.530
secs per century, I estimate that our ancestors a million years ago had a
day shorter than ours by 5,300 secs, or 1.47 hours, that is, 22.53 hours.

        The burning question is, what was the length of the day say 50
million years ago, still just a blink in geologic time, at a time when the
mammals were starting to proliferate? Or 100 million years ago during the
age of the dinasours. Seems that there wouldn't be time to get a good
night's sleep.

        Probably some geologic colleague already knows the answer to this
and can enlighten us.

                                Mike Quastel MD PhD
                                Head, Inst of Nuclear Medicine
                                Soroka Medical Center
                                Ben Gurion University of the Negev
                                POB 151, Beer Sheva, Israel 84101
                                Fax +972-7-6400765
                                Email: maay100@bgumail.bgu.ac.il

>Leap years are necessary because of the time required for the earth to move
>around the sun with respect to their relative positions. The tropical year,
>which keeps the seasons in their right places, is defined by the time for
>two consecutive returns of the sun to the vernal equinox (at the earth's
>equator). That is 365 days, 5 hours, 48 minutes, and 46 seconds in 1990
>(1997 World Almanac). It is decreasing by about 0.530 seconds per century.
>Hence, the tropical year is now about 365.2422 days. With the leap year
>system, there is an extra 3 days every 10,000 years. That's about an extra
>26 seconds per year. We could approximately correct by not allowing years
>divisible by 4,000 to be leap years. Luckily, we have astrophysicists and
>atomic clocks to help keep us on time.
>
>Although 1900 was not a leap year, the last year of the 20th century, the
>year 2000, will be a leap year. There will be a February 29,2000.
>
>I hope this is all there is on this issue.
>
>Best regards,
>
>Otto
>                *****************************************************
>                Prof. Otto G. Raabe, Ph.D., CHP
>                Institute of Toxicology & Environmental Health (ITEH)
>                     (Street address: Old Davis Road)
>                University of California, Davis, CA 95616
>                Phone: 916-752-7754     FAX: 916-758-6140
>                E-Mail: ograabe@ucdavis.edu
>                ******************************************************